Gamma Knife Radiosurgery For Vestibular Schwannomas: Long Term Results In 249 Patents.

Dheerendra Prasad1, Robert Fenstermaker2, Robert Plunkett2, Manjari Sharma2, Michael Kuettel2, Matthew Podgorsak2, Douglas Moreland2, Dhiren Shah2, Steven deBoer2, Harish Malhotra2

1Roswell Park Cancer Institute 2Roswell Park Cancer Institute, Buffalo, USA

Keywords: vestibular schwannoma, outcome, hearing function, radiosurgery, brain tumor

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     Careful objective evaluation of clinical and imaging outcomes of Gamma Knife Radiosurgery (GKRS) in patients with non NF-2 vestibular schwannomas.
     The purpose of validating the continued use of GKRS as a primary modality in the definitive management of Vestibular schwannomas.
     Two hundred forty-nine (249) consecutive patients with vestibular schwannomas treated with GKRS, were followed clinically and with serial imaging.
      Image analysis for volumetric assessment of outcome was performed with a intramurally developed and validated software package to provide objectivity. Data was mined with a PostgreSQL database and analyzed with SPSS Version 15.0. Minimum follow up of 2 years and follow up extending up to 12 years is available on all patients. Dose ranged from 10 -13 Gy to the edge of the tumor. Treatments were performed with model B and 4C units.
     Tumor control was obtained in 240 (96%) patients with volume reduction in excess of 15% was observed in 182 (73%). Increase in volume in 9 patients prompted repeat radiosurgery in 3 patients. No further management was required in 6 patients. Clinical adverse effects were observed in 4 patients (2%) and consisted of dizziness (1), facial weakness (2), hemifacial spasm (1) and hydrocephalus (1) patient. Hearing was preserved in 78% percent of patients with useful hearing at time of GKRS at 5 years. Facial paresis appeared postoperatively in two patients and improved to Grade I House Brackmann on corticosteroid treatment.
     This was a retrospective study.
     GKRS is offered as primary management of vestibular schwanommas.
     At our institution, it is an alternative to microsurgery on the basis of these findings.


Project Roles:

D. Prasad (), R. Fenstermaker (), R. Plunkett (), M. Sharma (), M. Kuettel (), M. Podgorsak (), D. Moreland (), D. Shah (), S. deBoer (), H. Malhotra ()